Flip chip technology is an alternative to wire bonding. Flip chip technology enables direct electrical connections between the electronic components of a chip and the corresponding supporting substrate. The electronic components are often mounted or coupled face down (i.e., “flipped”) on the semiconductor chips and connected, both electrically and physically, to the substrate by conductive bumps. Flip chips may be advantageous because the chip is directly attached (electrically and physically) to the semiconductor substrate, board, or carrier by the solder bumps.
Flip chips may be fabricated by a process that includes placing solder bumps on a semiconductor substrate. The solder bumps of the flip chip assembly provide an electrically conductive path from the chip to a semiconductor substrate on which the chip is mounted or coupled. The bumps also generally provide for the mechanical mounting or coupling of the chip to the semiconductor substrate. Some flip chip dies are provided with passivation layers to provide electrical stability by isolating transistor surfaces from the environment. Generally, a passivation layer may provide physical, chemical or electrical insulation/isolation, stability or separation between IC layers or components. A passivation layer may also facilitate the formation of thin film transistors or other components by, e.g., reducing electrical or chemical effects that might otherwise arise in adjacent components. In this regard, current leakage, parasitic capacitance or oxidation effects can be reduced or eliminated with a suitable passivation layer. Vias may be provided within the passivation layer to allow for electrical interconnects through the passivation layer to the aforementioned solder bumps.
However, with flip chip technology, issues can arise involving delamination of the passivation layer or adjacent layers during package assembly or subsequent use due to stress or strain. For example, advanced fabrication modes form passivation layers that may be sensitive to delamination under flip chip bumps during assembly.